High density microfacsimile system



July 25', 1967 R. s. BERGLUND ETAL 3,333,057

HIGH DENSITY MICROFCSIMILE SYSTEM 5 Sheets-Sheet l Filed Oct.

ffm/mail. WER/VER TZ'ORNEYS July 25, 1967 RQs. BERGLUND ETAL 3,333,057

HIGH DENSITY MICROFCSIMILEI SYSTEM 5 Sheets-Sheet El Filed Oct. 7, 1966 E m P 0 ,W w f p am Q mg 00 HN F F @l/f f /V lymw T wm, n MM F July 25, 1967 R. s. BERGLUND ETAL 3,333,057

HIGH DENSITY MICROFACSIMILE SYSTEM Filed OCT.. 7, 1.966

5 Sheets-Sheet 5 INVENTORS Pom-'AP75 EAPGL UND United States Patent ce Patented July 25, 1967 3,333,057 HIGH DENSITY MICROFACSIMILE SYSTEM Robert S. Berglund, North Hudson, Wis., and Thomas J.

Werner, North St. Paul, Minn., assignors to Minnesota Mining and Manufacturing Company, St. Paul, Minn., a corporation of Delaware Continuation of application Ser. No. 352,871, Mar.

18, 1964. This application Oct. 7, 1966, Ser. No.

This application is a continuation of S.N. 352.871, filed Mar. 18, 1964.

This invention relates to a new and very useful high density, high capacity, high speed microfacsimile system.

In one aspect this invention relates to apparatus comprising a unique combination of elements whereby fixed graphic material, including pictures, is first converted into a serial electrical output systematically representative of such graphic material. This output is then utilized to intensity modulate an electron beam. This modulated beam is then caused to scan a surface (scan field) systematically so that there is produced on such surface in micrographic form a representation or image of the original fixed graphic material. A suitable electron beam sensitive medium (not part of this invention) can be positioned upon the vsurface being scanned to record the micrographic image. Optionally included as an integral part of the apparatus of this invention is a special electron beam automatic raster transposition subsystem whereby a plurality of micrographic images are producible within a single scan field without mechanical movement of any portion of the system.

As previously indicated, a primary purpose of this invention is to produce electronically, micrographic images, that is, images Whose resolution capability is greater than 100 lines per mm. As those familiar Withthe production of micrographic images as by conventional optical means will appreciate, certain apparatus capabilities` for the production of such images are required. Thus, the equipment used must be capable of forming (for recording) a micrographic image having 100 lines/mm. or more on a surface. Another requirement is that a recorded micrographic image be capable of 'a large number yof total lines of resolution.

Those familiar with conventional video equipment will appreciate that the scanning electron beam used to image a conventional television type cathode ray tube has the capacity of producing from about 525 to 1000 total number yof lines in a scan field. When it is desired to use an electron beam to reproduce the graphic material such as,

for example, an 18 x 24 inch engineering drawing, it is not possible to get good reproduction of such materiall because the number of scan'lines in commercial video equipment is insufficient to record an image (micrographic or otherwise) in sufficient detail to permit subsequent adequate reproduction of the original input graphic material. Studies have shown that in order to adequately reproduce, for example, an 18 X 24 inch engineering drawing, about 4000 to 6000 scan lines are needed. In general, because of the information content of fixed graphic material, conventional video equipment is not suitable for use in recording and such reproducing.

When it is desired to form micrographic images using a scanning electron beam, not only is it necessary to have an adequate scan line density per image as just indicated, but also it is necessary to have an extremely small-sized beam spot. The diameter of such spot must be maintained over an entire scanning raster. Such small-sized spot requires a combined electron beam electron optical system containing in addition to conventional elements, means for accurately prefocusing the beam and for removing what would otherwise be excessive astigmatic aberrations.

It is evident that in general in a microfacsimile system wherein one scans at a line density of 100 lines per millimeter or more, it is necessary to have a constant spot size not greater than about microns in diameter and to maintain the spot dimensions continuously as an effective circular perimeter.

In a microfacsimile system it is necessary to provide means for accurately pre-focusing and for removing astigmatism from the beam. Conventional means such as Y visual observation of a fluorescing spot due to a stationary necessary for microfacsimile are involved, conventional visual focusing and astigmatic correction techniques are of little or no value. Therefore, a severe limitation heretofore existing in the art is overcome by employing prefocusing and astigmatism correction means which are not limited by the resolving power of optical lenses, or of the human eye, but which instead are limited only by the size of the prechosen, optimally shaped beam spot itself.

It is also desirable in a microfacsimile system to have apparatus capable of reproducing upon a single recording medium ,approximating the field of scan of the microfacsimile recording beam a plurality of separate micrographic images, each such microimage being in effect a high fidelity recording of a single, fixed graphic input.

So far as is known to us, no one has heretofore been able to overcome such problems and have apparatus for microfacsimile purposes using a scanning electron beam.

Thus, by the present invention there is provided apparae tus which not only provides an adequate line density for adequate reproduction of fixed graphic material, but which also has the capacity to record fixed graphic material in micrographic image formi. VOptionally and preferably apparatus ofthe present invention includes means for producing withina single scan field a plurality of separate,

discrete micrographic images.

Thus it is among the objects of the present invention to produce electronic apparatus for high speed, high capacity, high density microfacsimile using a modulated, scanning electron beam for micrographic image formation.

It is another object of this invention to provide apparatus of the class indicated having a compact, easily adjustable, commercially practicable sub -assembly which, from the seri-al electrical input providedv by a graphic scanner Vmeans, is adapted to forming micro-l graphic images having a resolution capability of not less than lines/millimeter using a synchronized modulated scanning, small spot, elect-ron beam.

It is a further object `of this invention to produce electronic microfacsimile 4apparatus having the capability to v produce within a single scan field of the modulated,

scanning electron beam used in micrographic image formation a plurality of discrete, separate micrographic im,-

ages without mechanical movement of any portion ofy the apparatus.

I lIt is another object of this invention to produce a'. method and apparatus for use in microfacsimile Wherecome apparent to those skilled in the art from a reading of the present specification taken together with the drawings wherein:

FIGURE 1 is a block diagram of one embodiment v,apparatus suitable for practicing this invention;

. of a focusing target;

FIGURES a, 5b, and 5c show cathode-ray tube displays of the target of FIGURE 4 during a focus and astigmatism correction operation which could be used with the embodiment of FIGURE 1.

Turning to the drawings there is seen in FIGURE 2 means for producing electron beam which is suitable for use in practicing the present invention. It is seen that lsuch means employs an electron source comprising a hairpin filament 10, a grid 11, for example of the Wehnelt type, and a centrally circularly apertured anode 12. Filament 10, grid 11, and anode 12 are of conventional construction. The filament, which can be constructed of tungsten, constitutes a cathode which is elevated at high negative potential with respect to ground. The electrons emitted by the cathode or filament 10 are accelerated by the field between the filament and the anode 12. The positioning or spacing of the filament 10 with respect to the grid 11 is such that the tip of the' filament 10 is in close proximity to the aperture 13 of grid 11. The grid 11 serves in a conventional and well understood manner to control electron current from the filament 10 passing to the anode 12. The anode 12 is typically positioned so as to be from about 1A: toV l/2 inch from the grid 11.

In the stream of electrons passing from the grid 11 to the `anode 12 is a cross-over point (not shown). The cross-sectional area of the electron stream at the crossover point is usually about 50 microns which is much too large for use in a microfacsimile system. To achieve demagnification sufficient to produce a beam spot diameter of a size suitable for the microfacsimile purposes of this invention, demagnfication atleast about 10 times is needed. Hence, the electron beam producing means of FIGURE 2 is equipped with an electron lens system or electron optical system. In general, electron beam demagnification is equal to the object to electron lens distance Idivided by the electron lens to cross-over distance.

For purposes `of this invention it is preferred to use electron optical systems having a plurality of lenses.

Electron optical systems preferred for use in practicing the present invention `also employ a plurality of centrally apertured plates. There is at least one such plate positioned in the vicinity of each lens. Each such plate is positioned normally to the beam axis and has the axis of its aperture aligned with the beam axis. Each -aperture has a diameter corresponding to the diameter desired for said beam at that position in the electron optical system.

Referring to FIGURE 2, there is seen a first electromagnetic lens 16, which can be located in the embodiment shown a short distance down along (i.e. aligned with) the beam axis from the anodeaperture 14. This lens 16 is chosen so as to have afshort focal length and also so asV to form a highly demagniied image of the original cross-over region; such demagnifiedy image is suggested at point 15 in FIGURE 2. This demagnified image 15 now becomes the object for the second lens 17.

Second lens 17 is located between first lens 16 and target 19. Lens 17 has a much longer focal length ythan that of Ilens 16; that is, has the capacity to reduce the image of the original cross-over region to a much smaller extent than does the first lens 16. Such long focal length is chosen because it is desired to maintain a considerable distance` between the second lens 17 and the target or scan field 19. Such a distance between the target 19 and the second lens 17 permits one to maintain a wide scan field using a relatively small beam deflection angle.

A first apertured plate 21 is inserted in axial alignment with the path of the beam at a point just before the first lens 116 to aid in limiting beam diameter, and to prevent electrons from striking the enclosing walls of the column (not shown) which encloses the entire electron beam producing means. The second magnetic lens 17 is axially aligned with the beam axis and is positioned further down along the beam axis relative to the first lens 16. A second apertured plate 22 is located just above the second lens 17. Plate 22 further serves to columnate the electron beam.

A third apertured plate 23 is positioned within the second lens 17. Plate 23 serves to limit beam diameter in the second lens to a value determined by spot size and desired deflection requirements so that the desired spot size can be maintained over an entire scan pattern or raster. The second lens 17 is positioned about 30 centimeters from the scan field 19. The scan field 19 is positioned so as to be in the focal plane for the second lens 17.

In addition to an electron source, an electron optical system, and a scan field 1-9, those skilled in the art will appreciate that an electron beam producing means requires an evacuatable envelope enclosing functional portions of said electron source, said electron optical system and said scan field. For the purposes of this invention it is necessary that the electron source and the electron optical system be so functionally associated together as to be adapted to produce an electron beam whose spot diameter is not greater than about 10 microns. The construction of electron beam producing means has been extensively investigated and is well known to those of ordinary skill in the art and consequently does not represent a patentable feature of the present invention. Details relating to the construction of such electron beam producing means are therefore no-t given herein. Among the extensive literature relating to the design and construction of electron beam producing means can be listed such references as Von Ardenne U.S. Patent No. 2,898,467 and V. E. Cosslett U. S. Patent No. 2,866,113. Electron beam producing means preferred for purposes of this invention employ, as suggested in FIGURE 2, two electromagnetic lenses and three apertured plates.

As those skilled in the art will appreciate, the grid r11 provides a means whereby an electron beam generated by the assembly shown in FIGURE 2 can be intensity modulated.

Functionally associated with the electron optical system of the electron beam producing means is a beam deflection means. While any such means can be employedl in an electron beam producing means useful in this invention, the embodiment described herein employsv a conventional magnetic defiection yoke 18. Yoke 18 is positioned between the second lens 17 and the scan field 19. The yoke 18 is of conventional design and is driven by a vertical deflection amplifier 112a and by a horizontal defiection amplifier 112b, each of whose outputs are conventional sawtooth wave forms (see FIGURE l). For purposes of this invention, the beam deflection means should be adapted to cause the electron beam to move over predetermined portions of the scan field and have a scan line density of not less than' about 100 scan lines per millimeter.

In using an electron beam means as hereinabove described in combination with a deflection means, it has been found very desirable for producing micrographic images in accordance with the teachings of this invention to employ stigmator means functionally associated with said electron optical system and with said beam defiection means. As those skilled in the art will appreciate, such stigmator means enables one to preoptimize a beam so as to both optimally focus said beam' and minimize its astigmatic aberration.

In FIGURE 3 is shown one form of stigmator useful for this invention. Here eight rods 26 are mounted on a stigmator support 27. Stigmator support 27 is disk-shaped and has an aperture 31 axially extending therethrough. The stigmator support is mounted within the second lens 17 as suggested in FIGURE 2. The rods 26 are mounted upon one face of stigmator support 27 in a circumferential fashion so as to be equally spaced about the axis of the electron beam and so as to have their respective axes each extend generally parallel with the beam axis. Each rod 26 is insulatedfrom the stigmator support 27 by insulating material 28. Each rod 26 is connected to a lead 29 and all eight leads are connected to a stigmator control panel 114. This stigmator is of the electrostatic type. By imposing predetermined voltages upon individual ones of the rods 26, astigmatic spot aberrations are controlled.

In a microfacsimile system of the invention one employs scanner means for systematically scanning input information and for converting same into a serial electrical output systematically representative thereof. For this purpose any form of conventional video camera can be used, provided the raster associated with such scanner means has sufiicient scan lines to read out all the information in fixed graphic input material. The number of scan lines needed in a raster can Vary, although studies have shown that at least about 1000 lines are needed for an 81/2 x 11 sheet of paper.

The analogue wave form output of the scanner means, such as a video picture generator, is coupled by conventional techniques to thereby modulate the electron beam used to produce the microfacsimile. Suitable coupling techniques inclu-de conventional transmission lines such as coaxial cables, telephone lines and radio waves, and the like. Y

In order to achieve the proper synchronization between the scannerV means and the scanning electron beam forming the micrographic image, a synchronizing generator means is provided. This synchronizing generator electronically interconnects the scanner means with the electron beamY producing means. Synchronization can be achieved .in any one of a variety of ways well known to those of ordinary skill in the art.V

A preferred embodiment of this invention characterized by a beam spot significantly smaller than microns employs beam focusing means whereby the electron beam used in this microfacsimile system is prefocused using a secondary electron emission readout technique so as to -both optimally focus the beam and minimize beam astigmatic aberrations without the limitations associated with techniques requiring direct visual observation of the spot impact area on, for example, a fluorescent screen.

Thus, before using an embodiment of a microfacsimile system of this Vinvention to form micrographic images, it is preferable to focus the beam and completely remove beam astigmatism thereby to produce a beam having the desired spot characteristics. In this invention, focusing involves the temporary positioning within the scan field of a beam responsive material which provides a detectable image of the impinging beam. ToV practice the focusing means, one employs a conductive test target or focusing target 120 (see FIGURE l) which has formed thereon an image having a substantially different secondary electron emission character from that of the adjoining surface. At least a portion of such image is formed of lines which are normal to the beam scan pattern. Furthermore, the lines of the image have widths smaller than the desired focused beam diameter. A suitable focusing target 120 is shown in FIGURE 4. Here the target 120 is shown in FIGURE 4. Here the target 120 has formed thereon a simple cross, l119 as the conductive test target image. The image 119, for example, can be constructed of vapordepositedl gold and the focusing target background surface can be aluminum, although those skilled in the art` will appreciate that any conventional combination of materials having dissimilar secondary electrongcharacteristics can be used. The lines of the cross image 119 are so chosen as to have widths smaller than thosel of the desired focus beam diameter. In this invention, the lines of such an image cross 119 will always be smaller than 10 microus.

When the focusing target 120 (FIGURE l) is mounted in the scan field 19, and the focusing target 120 (FIG- URE 1) is grounded by means of a resistor 118, a voltage develops across the resistor 118 when the target 120 is scanned with an electron beam, as for example, a beam produced in an apparatus in the character indicated n FIGURE 2.

As the beam scans the focusing target 120, a serial secondary electron emission readout of the cross image 119 results. This serial secondary electron emission readout signal is amplified by an amplifier 121 (see FIGURE 1) and displayed on a cathode ray tube television monitor 122. The monitor 122 and the defiection or raster pattern of the readout beam is synchronized by synchronizing generator 100.

If the scanning beam is elliptical in shape due to an astigmatism, one or the other of the arms of the image cross will not be the same on the monitor 122 in the vertical or in the horizontal direction. Astigmatism cor- -rection and focusing correction involve reshaping the beam as it scans the image cross 119 by adjusting the current in lens 17 and/or stigmator until the'beam has a circular, smallest desired diameter condition, wherein the display of the image cross 1'19 on the cathode ray tube of monitor 122 has the same respective proportions as the original image cross 119 on the focusing target 120.

For example, in FIGURE 5A is shown an image of the cross 119` on the cathode ray tube for monitor 122. Here an elliptical spot is shown having a major axis in the vertical direction. As a beam scans from left to right across the vertical bar ofthe cross 119, the width of the vertical bar on the monitor will be the desired proper Width, but when the ysame beam scans vertically down to the point where it intersects the horizontal bar of the cross 119, the vertical width of the horizontal bar will be lengthened by an amount proportional to the elongation of the spot in the vertical direction. In FIGURE 5B is shown a display on the cathode ray tube of manitor 122 of an elliptical scanning spot wherein the major axis is in the horizontal direction. In this instance the vertical bar of cross '119 is enlarged on the monitor 122 display.

As indicated, to correct for such aberrations, onev adjusts the stigmator control 114 and the focus adjustable current source 113. One procedural method is to shut off the stigmator 20 completely, bring the scanning beam into sharpest possible focus using focusing current from focus current source 113, and then turn on the stigmator 20 and adjust the stigmator voltages with stigmator con-y trol 114 to bring the beam spot into circular configuration as the monitor 122 readout display is observed, a condition as shown in FIGURE 5C. It will be appreciatedthat in the description above, the choice of a cross is merely for illustrative purposes. In general, the focusing target 120, in order to be useful in practicing the focusing method and means of this invention, need have only areas thereon which differ in their. secondary emission characteristics. Thus scratches, or circular defects of substantially known dimensions (which are smaller than the optimum beam diameter desired), are all that is necessary for image purposes upon the focusing target 120.

It will be appreciated that the focusing method and means of this invention, applied to a demountable electron optical system (such demountable electron optical systems are preferred for the use in this invention for forming microfacsimile images) is far superior to the conventional techniques involving direct or magnified observation of a stationary fluorescing spot since the focusing method and means are not limited by either phosphor resolution capabilities or electron beam spot size, factors which are important in the microfacsimile system of this invention, owing to the small size of the spot diameter used for micrographic image formation.

With the electron beam used for micrographic image formation optimally focused and corrected for astigmatic aberrations, one can form micrographic images in accordance with the invention. Referring to the embodiment shown in FIGURE 1, graphic input material to be formed into a micrographic image is positioned before scanner means, in this case picture generator 101. The graphic input is scanned in a raster pattern and the output is a serial electrical output systematically representative thereof, which is in the form of an analogue' signal containing the picture and/ or synchronizing information. The synchronizing information is in the form of pulses obtained from the synchronous generator '100.

The analogue electrical signal is amplified by the video amplifier 102 and the output from amplifier 102 is coupled to modulator 104. In modulator 104 the output from the video amplifier 102 is used to modulate the output of the oscillator 103. T-he ramplitude modulated wave form signal produced from modulator 104 is coupled by means of a driver 105 and high voltage isolation transformer 106 to vthe detector 107 in the high voltage isolation grouping of equipment used with the electron source. The detector in effect demodulates the carrier sinusoid generated by oscillator 103.

The detected picture information is amplified by video amplifier 108. The voltage output of amplifier 108 contains serial picture information from the scanner means or picture generator 101 and is used to i-ntensity modulate the control grid 11 of the electron beam.

The electron beam -defiector yoke 18 is driven by means of horizontal and vertical deflection generator 112, synchronized by generator 100. The deflection currents produced by generator 112 are prechosen s-o as to be of sufficient |magnitude to produce the desired deflection sweep size upon the scan field 19.

Instead of forming a single micrographic image, possibly extending over the entire scan field 19, one can, in accordance with the teachings of this invention, optionally for-m a plurality of micrographic images containing the same resolution potential, in terms of lines of resolution per millimeter, but having fewer total lines per irnage.v In this situation, one employs a special electron beam automatic raster transposition subsystem which enables one to form a plurality of separate micrographic images within a single scan field wit-hout mechanical movement of any portion of the system, including the recording medium (not shown) within the scan field 19 (see FIG- URE 1).

It will be appreciated that the number of scan lines in a single raster of the scanner means (e.g. picture generator 101) is such that a plurality of separate raster patterns can be formed in one scan field. Although one can use scanner means capable of forming a plurality of separate raster patterns over a xed input field area, for purposes of this invention it is usually preferred to employ scanner means, such as a picture -generator 101, which have the entire viewing field formed by a single raster, the total number of lines in such raster being such that the desired plurality of separate raster patterns can be formed in one scan field 19.

For example, assuming the entire scan field 19 is being employed and that the deflecting yoke 18 is operating in the maximum deflection mode possible and that the recording beam velocity is constant over the entire scan field, it is necessary to change the horizontal and the vertical scan deflection by changing t-he vertical and horizontal synchronizing pulse rate by a factor of (N) to the 1/2 power where N is the `number of microimages to be recorded in a single scan iield wherein the same number of microimages are to be formed horizontally as vertically.`

' In the embodiment shown in FIGURE l there is provided a selector switch, 110A which changes the micrographic image formation pattern from one occupying the entire scan field 19 to one wherein a plurality of micrographic images are formed in a single scan field, 19. For example, when switch A is closed, an enable voltage is delivered from the exposure counter or raster counter 110 `to the synchronizing generator 100 which changes the system synchronizing rate by the desired factor, say N'2.

Exposure counter 110 is la conventional binary counter capable of counting from 1 to N (where N is the number of subscan images to be recorded), which, at the completion of each subscan, receives -a verification pulse from the picture generator 101 `and delivers a binary code indicative of the number of subscans that have been recorded. This binary code is delivered to the pre-programmed D.C. centering means which is a conventional digital to analogue converter which produces, in conjunction with the vertical deflection means 112, discrete D.C. current levels in the vertical and horizontal yoke windings of magnetic yoke 18. Thus we have provided means of recording N successive microimages without resort to mechanical positioning of any part of the microfacsimile system.

Because of the fact that the electron beam producing means, with its .associated scan field, means for intensity modulating the beam, beam deliection means, etc., are usually enclosed in la vacuum chamber, it is commonly desirable to include within such chamber upon opposite sides of the scan field 19 or in another or other suitable position, transport means adapted to advance recording medial step-wise into the scan field 19 whenever that portion of the recording media in the scan field is to be advanced.

In general, there are two types of transport means employed. In one type, the recording media comprises a plurality of separate discrete sheets or sheet-like constructions, and each such construction is adapted to receive a plurality of micrographic images Vas recordings thereupon. In this situation, the transport.v means is adapted to sequentially advance one individual sheet-like recording medium at a time into the scan field, and to hold such sheet-like recording `medium with-in the scan field for the period of time when microgrlaphic images are being recorded thereon. Commonly during this period the automatic sequential raster transposition subsystem of this invention is in operation s-o that a plurality of separate discrete micrographic images a-re being formed on an individual sheet-like fonm of recording medium.

In' the second type of transport means, the recording medium is in the form of a continuous tape-like form and the transport means is adapted to advance the tapelike recording media step-wise into the scan field and then onto a windup reel from a pay-off reel. During the recording sequence, the film is held within the scan field 1 9 for the period of time necessary either to form a slngle micrographic image thereupon or to form ya plurality of subscan images thereupon. As soon as the desired number of images are formed on the tape, the transport means is used to advance to a different and new unexposed film portion, as respects the scan field 19.

Independently of the type of transport means em ployed, however, the transport means is rendered operative by the output of an And circuit whose inputs are'an enable voltage originating from the exposure counter 110, Iand a picture verification pulse from picture .generator 101.

' Thus at the completion of N recording, unexposed recording media advances into the scan field by either transport means described above.

What is claimed is: t

1. Apparatus for automatic sequential image transposition in a micrographic image recording system,said system including means for generating an image, electron beam producing means for producing an electron beam 3,333,057 9 10 which forms said generated image directly on a recording the scanning'sequence of said scanner means is submedia, said apparatus comprising Y stantially identical to that of said beam deiiection means for determining when a generated image is v .means,

formed by said'electron vbeam in response to said (g) stigmator means functonally'associated with said image generating means; and electron optical system and with said beam deflection preprogrammed means adapted to produce and apply means adapted to both optimally focus said beam and vdiscrete prechosen electrical signals to a beam deiiecminimize beam astigmatic aberrations,

tion means so as to transpose said electron beam to a (h) a raster counter adapted to determine the start and prechosen position to record a subsequent generated the iinish of a raster pattern performed by said scanimage in response to said determining means deter- 10 ner means and further adapted to produce an indicatmining the 'recording of a generated image onto said ing pulse at the finish of each such raster pattern, recording media in response to said image generating (i) pre-programmed raster centering means adapted to means. deliver discrete, prechosen direct current values to 2. Apparatus set forth in claim 1 wherein said prepro-i said beam deiiection means responsive to said indigrammed means includes 15 eating pulse so as to center a'raster pattern in a precontrol means operatively coupled to beam deflection chosen position in said scan field,

" means for producing land applying discrete predeter- (i) the number of scan lines in a single raster of said mineddirect current signals to said beam deflection scanner means being such that :a plurality of sepameansto transpose said electron beam into a pre- `rate raster patterns can be formed in one scan iield, chosen position which is in horizontal alignment adja- (k) focusing means adapted toj substantially completely cent a generated image. remove b'eam astigmatism and produce the desired 3. The apparatus of claim 1 wherein said prepro- SpOt SiZegrammed means includes 7. A high density, high speed, high capacity microfaccontrol means operatively connected to said beam de- Simile System comprising flection means for producing and applying discrete (a) scanner means for systematically scanning input inpredetermined direct current signals to said beam deformation and for Converting Seme into a serial eleci'lecting means to transpose said electron beam into a trical output Systematically I'ePreSentative thereof, prechosen position which is in vertical alignment adjai (b) an electron bearn Producing mcans including an cent a generated image. electron source, an electron optical system function- 4, The apparatus of claim 1 further including 30 ally associated wtih said electron source and adapted selecting means operatively coupled to said determining to Produce in cooperation With Said Sollree an elecmeans for applying electrical signals to said deter. tron beam smaller than about 10 microns in diameter, mining means to modify said preprogrammed means a scan field for Said electron beam, and an evacuatfor operating said beam deflection means to arrange able envelope enclosing functional Portions of Said said prechosen positions in an aligned pattern Whereelectron source, said electron optical Systern, and Said by a plurality of separate aligned generated images Scan field, forms a micrographic image, (c) said electron source comprising a hairpin-type fila-J 5. The apparatus ot claim 4 wherein said preproment, a cylinder-type grid, and a centrally circularly grammed means includes n apertured anode,

means responsive to said selecting means for trans- 40 (d) said optical system having a plurality of lenses, posing said electron beam to said prechosen positions each aXially aligned With and longitudinally spaced in a sequence to produce a first micrographic image along the axis of said beam, the lens nearest said having a first number of generated images and causd scan iield having a relatively long focal length c0111- ing said beam deflection means to transpose said elec- Pared to Other lenses in said System, tron beam into a subsequent prechosen position rela- (e) said electron optical systern further having a Plutive to said first micrographic image to produce a seerality of plates each with a generally centrally located ond aligned micrographic image having a second circular aperture therein, there being at least one such number of generated images, plate positioned in the vicinity of each lens, each such 6. A high density, high speed, high capacity mocrnfaeplate being positioned normally to said beam axis simile System adapted for producing micrographic images and having the aXis of its aperture aligned With said upon a recording medium, said system comprising beam axis, each laperture having a diameter corre- (a) scanner means for systematically scanning input v sponding to the diameter desired fOr Said beam at information Iand for converting same into a Seria] that positiOtl in Said electron Optical System, electrical output systematically representative thereof, (f) Signal coupling means adapted to interconnect ont- (b) an electron beam producing means including an Put from said Scanner means With said grid to intenelectron source, anelectron optical system functionsity modulate Said bearn, ally associated with said electron source and adapted (s) beam deection means functionally associated with to produce in cooperation with said electron source said electron optical System and adapted to cause an electron beam not greater than about 10 microns Said beam to deiiect through a maXirnum deflection in diameter, a scan field for said electron beam, and of about 40 rnrnand to move over predetermined evacuatable envelope enclosing functional portions Portions of Said scan iield in a raster Pattern having of said electron source, said electron optical system, not less than about 100 Scan lines Per millimeter, and said Scan field, (h) synchronization means adapted to slave said scan- (c) means functionally associated with said electron nel' mean? With Said beam fieectiob means S0 that source for intensity modulating said beam the scanning sequence of said scanner means is sub- (d) Signal coupling means adapted to deliver said Sep stantially identical to that of said beam deflection rial electrical output from said scanner means to said meins intensity modulating means (i) st1gmator means functionally assoc1ated with said lectron optlcal system and with sald beam deflection (e) beam delectlon means functlonally assoclated with e said electron optical system and adapted to cause means-m1d adapted to both optimally focus Said beam and minimize its astigmatic aberrations during scansaid beam to move over predetermmed portlons of ning sald scan eld m a raster Pattefn having not less (j) a conductive focusing target Whose surface has than about .10Q scan lines Per millimeter, formed thereon an image having a substantially dif- (f) synchronization means adapted to slave said scanferent secondary electron emission character from ner means with said beam deflection means so that that of thev adjoining surface, at least a portion of said image being formed of lines which are normal to the beam scan pattern, said lines having widths smaller than the desired focused beam diameter, said test target being positioned'in said scan field,

(k) means grounding said test target,

(l) means for amplifying the serial secondary electron emission output produced between said test target and ground when said test target is scanned by an unmodulated electron beam from said electron beam producing means,

.(m) a display device adapted to visually display signals from said means for amplifying,

(n) synchronization means adapted to slave said elec- .tron beam producing means with said display device so that the scanning sequence of said beam is substantially identical to that of said display device.

' 8. Apparatus for automatically sequentially raster transposition in a microfacsimile system, said system including scanner means, electron beam producing means with an associated scan field, means for intensity modulating said beam, beam deflection means, synchronization means, yand coupling means, said apparatus comprising (a) a raster counter adapted to determine the start and the linish of a raster pattern performed by said scanner Ameans and further adapted to produce an indicatf ing pulse at the finish of each suchraster pattern, (b) pre-programmed raster centering means adapted to deliverdiscrete, prechosen direct current values to said beam deflection means responsive to said indicating pulse so as to center a raster pattern in a prechosen position in said scan field, (c) the number of scan lines in a single raster of said scanner means being such that a plurality of separate raster patterns can be formed in one scan ield.

References Cited UNITED STATES PATENTS 3,221,099 11/ 1965 Breitbord 178--72 3,301,949 1/1967 Ullery V 178-6.8

20 `OHN W. CALDWELL, Acting Primary Examiner.

R. L. RICHARDSON, Assistant Examiner.

UNITED STATES PATENT oFFIoE CERTIFICATE OE CORRECTION Patent NO 3 ,553 ,O57 July 25 1967 Robert S. Berglund et al.

that error appears n the above numbered patlt is hereby certified that the said Letters Patent should read as ent requiring correction and corrected below.

Column S lines 68 to 69 strike out "Here the target l2() is shown 1n FIGURE 4 column 6 line 44 for "manitor" read monitor Column 8 line 31 for "medial" read media column 9, line 49, for "mocrofac" read microfacline 59 after "and" insert an column l0 line 30 for "wtih" read --nwith Column ll, line 17, for "automatically sequentially" read automatic sequential Signed and sealed this 25th .day of June 1968.

(SEAL) Attest:

EDWARD I. BRENNER Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

1. APPARATUS FOR AUTOMATIC SEQUENTIAL IMAGE TRANSPOSITION IN A MICROGRAPHIC IMAGE RECORDING SYSTEM, SAID SYSTEM INCLUDING MEANS FOR GENERATING AN IMAGE, ELECTRON BEAM PRODUCING MEANS FOR PRODUCING AN ELECTRON BEAM WHICH FORMS SAID GENERATED IMAGE DIRECTLY ON A RECORDING MEDIA, SAID APPARATUS COMPRISING MEANS FOR DETERMINING WHEN A GENERATED IMAGE IS FORMED BY SAID ELECTRON BEAM IN RESPONSE TO SAID IMAGE GENERATING MEANS; AND PREPROGRAMMED MEANS ADAPTED TO PRODUCE AND APPLY DISCRETE PRECHOSEN ELECTRICAL SIGNALS TO A BEAM DEFLECTION MEANS SO AS TO TRANSPOSE SAID ELECTRON BEAM TO A PRECHOSEN POSITION TO RECORD A SUBSEQUENT GENERATED IMAGE IN RESPONSE TO SAID DETERMINING MEANS DETERMINING THE RECORDING OF A GENERATED IMAGE ONTO SAID RECORDING MEDIA IN RESPONSE TO SAID IMAGE GENERATING MEANS.
 4. THE APPARATUS OF CLAIM 1 FURTHER INCLUDING SELECTING MEANS OPERATIVELY COUPLED TO SAID DETERMINING MEANS FOR APPLYING ELECTRICAL SIGNALS TO SAID DETERMINING MEANS TO MODIFY SAID PREPROGRAMMED MEANS FOR OPERATING SAID BEAM DEFLECTION MEANS TO ARRANGE SAID PRECHOSEN POSITIONS IN AN ALIGNED PATTERN WHEREBY A PLURALITY OF SEPARATE ALIGNED GENERATED IMAGES FORMS A MICROGRAPHIC IMAGE. 